1. Field of the Invention
This invention relates to a solid strong acid catalyst and more particularly, it is concerned with a solid strong acid catalyst in which sulfate (SO.sub.4) and Group VIII metals or Periodic Table are supported on hydroxides or oxides of Group IV metals of Periodic Table and/or hydroxides or oxides of Group III metals of Periodic Table, and a process for the production of the same.
2. Description of the Prior Art
As reactions in the petroleum refining and petrochemical industry, there are catalytic cracking, catalytic reforming, hydrodesulfurization, isomerization, alkylation of aliphatic and aromatic hydrocarbons, and polymerization, etc., and it has been recognized that as to the catalysts used for these reactions, the acid property thereof is one of important factors for reactivity. In the field of the so-called C.sub.1 chemistry using methanol or synthesis gas as a raw material, wherein various studies or developments have eagerly been made lately, solid acid catalysts, typically of which are metal silicates, play an important role, as well known in the art.
Generally, it is considered that there is an optimum value in the solid acid strength required for a certain reaction and on the other hand, it is also known that when using a "superacid" defined as a stronger acid than 100% sulfuric acid (Cf. "Superacids and Superbases" by Kozo Tanabe and Ryoji Noyori, published by Kodansha Scientific (1980)), skeletal isomerization reactions of paraffins proceed even at room temperature. However, the solid superacid catalysts of the prior art have drawbacks in that large amounts of by-products consisting predominantly of cracked products are formed in addition to the object product and the active sites are poisoned by carbonaceous materials secondarily formed so that the catalyst life is shortened that the use of such catalysts is impractical. In actual fact, therefore, evaluation of the activity of the catalyst has been carried out by prolonging the contact time largely to increase the efficiency using a reaction test apparatus of a closed cycle system.